Cast Operator (#5149)

* Cast Operator

Cast input variable to other data type

* Fix compile error

* Add cast op

* Follow comments

paddle/framework/data_type.h

@@ -34,5 +34,25 @@ inline DataType ToDataType(std::type_index type) {
   }
 }
 
+template <typename Visitor>
+inline void VisitDataType(DataType type, Visitor visitor) {
+  switch (type) {
+    case DataType::FP32:
+      visitor.template operator()<float>();
+      break;
+    case DataType::FP64:
+      visitor.template operator()<double>();
+      break;
+    case DataType::INT32:
+      visitor.template operator()<int>();
+      break;
+    case DataType::INT64:
+      visitor.template operator()<int64_t>();
+      break;
+    default:
+      PADDLE_THROW("Not supported");
+  }
+}
+
 }  // namespace framework
 }  // namespace paddle

paddle/framework/op_registry.h

@@ -162,6 +162,10 @@ class OpKernelRegistrar : public Registrar {
   REGISTER_OPERATOR(op_type, op_class, _GradOpDescMaker_##grad_op_type##_, \
                     op_maker_class);
 
+#define REGISTER_OP_WITH_KERNEL(op_type, ...)                         \
+  REGISTER_OPERATOR(op_type, ::paddle::framework::OperatorWithKernel, \
+                    ##__VA_ARGS__)
+
 #define REGISTER_OP_WITHOUT_GRADIENT(op_type, op_class, op_maker_class) \
   REGISTER_OPERATOR(op_type, op_class, op_maker_class)
 

paddle/operators/cast_op.cc

@@ -0,0 +1,73 @@
+/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserved.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License. */
+
+#include "paddle/operators/cast_op.h"
+#include "paddle/framework/op_registry.h"
+
+namespace paddle {
+namespace operators {
+
+class CastOpProtoMaker : public framework::OpProtoAndCheckerMaker {
+ public:
+  CastOpProtoMaker(framework::OpProto *proto,
+                   framework::OpAttrChecker *op_checker)
+      : OpProtoAndCheckerMaker(proto, op_checker) {
+    AddInput("X", "the input tensor of cast op");
+    AddOutput("Out", "the output tensor of cast op");
+    AddComment(R"DOC(Cast operator.
+cast the input tensor to other data type.
+)DOC");
+    AddAttr<int>("out_data_type", "output data type");
+    AddAttr<int>("in_data_type", "input data type");
+  }
+};
+
+class CastOpInferShape : public framework::InferShapeBase {
+ public:
+  void operator()(framework::InferShapeContext *context) const override {
+    PADDLE_ENFORCE(context->HasInput("X"), "The input of cast op must be set");
+    PADDLE_ENFORCE(context->HasOutput("Out"),
+                   "The output of cast op must be set");
+    context->SetOutputDim("Out", context->GetInputDim("X"));
+    context->ShareLoD("X", "Out");
+  }
+};
+
+class CastOpGradMaker : public framework::SingleGradOpDescMaker {
+ public:
+  using framework::SingleGradOpDescMaker::SingleGradOpDescMaker;
+
+ protected:
+  std::unique_ptr<framework::OpDescBind> Apply() const override {
+    auto grad = new framework::OpDescBind();
+    grad->SetType("cast");
+    grad->SetInput("X", OutputGrad("Out"));
+    grad->SetOutput("Out", InputGrad("X"));
+    grad->SetAttr("out_data_type", GetAttr("in_data_type"));
+    grad->SetAttr("in_data_type", GetAttr("out_data_type"));
+    return std::unique_ptr<framework::OpDescBind>(grad);
+  }
+};
+
+}  // namespace operators
+}  // namespace paddle
+
+namespace ops = paddle::operators;
+using CPU = paddle::platform::CPUPlace;
+REGISTER_OP_WITH_KERNEL(cast, ops::CastOpGradMaker, ops::CastOpInferShape,
+                        ops::CastOpProtoMaker);
+REGISTER_OP_CPU_KERNEL(cast, ops::CastOpKernel<CPU, float>,
+                       ops::CastOpKernel<CPU, double>,
+                       ops::CastOpKernel<CPU, int>,
+                       ops::CastOpKernel<CPU, int64_t>);

paddle/operators/cast_op.cu

@@ -0,0 +1,22 @@
+/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserved.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License. */
+
+#include "paddle/operators/cast_op.h"
+
+template <typename T>
+using CastOpKernel =
+    paddle::operators::CastOpKernel<paddle::platform::GPUPlace, T>;
+
+REGISTER_OP_GPU_KERNEL(cast, CastOpKernel<float>, CastOpKernel<double>,
+                       CastOpKernel<int>, CastOpKernel<int64_t>);

paddle/operators/cast_op.h

@@ -0,0 +1,64 @@
+/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserved.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License. */
+
+#pragma once
+
+#include "paddle/framework/data_type.h"
+#include "paddle/framework/framework.pb.h"
+#include "paddle/framework/op_registry.h"
+#include "paddle/platform/transform.h"
+
+namespace paddle {
+namespace operators {
+
+template <typename InT, typename OutT>
+struct CastOpTransformFunctor {
+  HOSTDEVICE OutT operator()(InT in) const { return static_cast<OutT>(in); }
+};
+
+template <typename Place, typename InT>
+struct CastOpFunctor {
+  const framework::Tensor* in_;
+  framework::Tensor* out_;
+  const platform::DeviceContext& ctx_;
+  CastOpFunctor(const framework::Tensor* in, framework::Tensor* out,
+                const platform::DeviceContext& ctx)
+      : in_(in), out_(out), ctx_(ctx) {}
+
+  template <typename OutT>
+  void operator()() const {
+    auto* in_begin = in_->data<InT>();
+    auto numel = in_->numel();
+    auto* in_end = in_begin + numel;
+    auto* out_begin = out_->mutable_data<OutT>(ctx_.GetPlace());
+    platform::Transform<Place> trans;
+    trans(ctx_, in_begin, in_end, out_begin,
+          CastOpTransformFunctor<InT, OutT>());
+  }
+};
+
+template <typename Place, typename InT>
+class CastOpKernel : public framework::OpKernel<InT> {
+ public:
+  void Compute(const framework::ExecutionContext& context) const override {
+    auto* in = context.Input<framework::Tensor>("X");
+    auto* out = context.Output<framework::Tensor>("Out");
+    framework::VisitDataType(
+        static_cast<framework::DataType>(context.Attr<int>("out_data_type")),
+        CastOpFunctor<Place, InT>(in, out, context.device_context()));
+  }
+};
+
+}  // namespace operators
+}  // namespace paddle

python/paddle/v2/framework/layers.py

@@ -5,7 +5,7 @@ import re
 
 __all__ = [
     'fc', 'data', 'cross_entropy', 'conv2d', 'pool2d', 'embedding', 'concat',
-    'StaticRNN'
+    'StaticRNN', 'cast'
 ]
 
 
@@ -163,6 +163,18 @@ _create_op_func_('mul')
 _create_op_func_('dropout')
 
 
+def cast(x, data_type, program=None):
+    helper = LayerHelper('cast', **locals())
+    out = helper.create_tmp_variable(dtype=data_type)
+    helper.append_op(
+        type='cast',
+        inputs={'X': [x]},
+        outputs={'Out': [out]},
+        attrs={'in_data_type': x.data_type,
+               'out_data_type': out.data_type})
+    return out
+
+
 def concat(input, axis, program=None, init_program=None):
     helper = LayerHelper('concat', **locals())
     if not isinstance(input, list) and not isinstance(input, tuple):

python/paddle/v2/framework/tests/test_cast_op.py

@@ -0,0 +1,26 @@
+import op_test
+import unittest
+import numpy as np
+import paddle.v2.framework.core as core
+
+
+class TestCastOp(op_test.OpTest):
+    def setUp(self):
+        ipt = np.random.random(size=[10, 10])
+        self.inputs = {'X': ipt.astype('float32')}
+        self.outputs = {'Out': ipt.astype('float64')}
+        self.attrs = {
+            'in_data_type': int(core.DataType.FP32),
+            'out_data_type': int(core.DataType.FP64)
+        }
+        self.op_type = 'cast'
+
+    def test_check_output(self):
+        self.check_output()
+
+    def test_grad(self):
+        self.check_grad(['X'], ['Out'])
+
+
+if __name__ == '__main__':
+    unittest.main()